Sulphur cement generally refers to a product comprising at least sulphur and a filler. To improve the properties of the sulphur cement, the sulphur may be modified using a sulphur modifier. Such modifiers are known in the art.
Usual sulphur cement fillers are particulate inorganic materials.
Sulphur cement-aggregate composites generally refer to a composite comprising both sulphur cement and aggregate. Examples of sulphur cement-aggregate composites are sulphur mortar, sulphur concrete and sulphur-extended asphalt. Sulphur-extended asphalt is asphalt, i.e. typically aggregate with a binder that contains filler and a residual hydrocarbon fraction, wherein part of the binder has been replaced by sulphur, usually modified sulphur.
It is known to use organosilane compounds as a stabilising agent in sulphur cement or sulphur cement-aggregate compositions to improve water stability. In U.S. Pat. No. 4,164,428 for example, a modified sulphur composition (often referred to a plasticized sulphur composition) comprising at least 50% by weight of sulphur, a sulphur modifier (often referred to a sulphur plasticizer), a finely divided particulate mineral suspending agent, and an organosilane stabilising agent is disclosed. It is mentioned that suitable organosilanes have the general molecular formula R—Si(OR′)3, wherein R′ is a low molecular weight alkyl group and R is an organic radical having at least one functional group, usually bonded to the silicon atom by a short alkyl chain. Gamma-mercaptopropyltrimethoxysilane is mentioned as a preferred organosilane.
In U.S. Pat. No. 4,376,830 a sulphur cement-aggregate composition comprising a sulphur cement and an aggregate containing an expansive clay and processes for preparing such compositions are disclosed. The processes, and resulting compositions, are characterised by the addition of certain organosilane compounds in the composition prior to solidifying (cooling) the composition. It is mentioned that suitable organosilanes have the formula Z—Si(R1R2R3), wherein R1, R2 and R3 may be lower alkoxy groups and Z is an organic radical attached to Si via a carbon atom and has at least one molten-sulphur reactive group. Z may for example be mercaptoalkyl. Gamma-mercaptopropyltrimethoxysilane is mentioned as a preferred organosilane. Gamma-mercaptopropyltrimethoxysilane is very toxic and has a very unpleasant smell. The resulting solidified composition has improved water stability. However, there is still room for improvement of the water stability of prior sulphur cement-aggregate composition.